Large PDF files can be slow to sync to your reMarkable and may exceed limits in the reMarkable cloud. The large-file optimizer in Klass-RM Uploader automatically shrinks oversized PDFs before uploading them - without you having to do anything.
This feature is free for everyone. It is Mac-only (the iOS and macOS share extensions do not apply optimization on iPhone/iPad due to memory limits).
How it works
When you upload a PDF, the app checks its file size. If it is above your configured threshold (default: 100 MB):
- The app rebuilds the PDF by re-encoding and downsampling the pages to a lower resolution. This also flattens any layers and annotations.
- If the resulting file is still too large, the app splits it into multiple parts named
"Document (1 of 3).pdf","Document (2 of 3).pdf", and so on. - Each part uploads separately to your reMarkable.
Files under the threshold upload without any changes.
Configuring the optimizer
Go to Settings > Conversion to adjust the optimizer:
- Mode: Choose On (default) or Off. When Off, files upload as-is regardless of size.
- Size threshold: The file size above which optimization kicks in. Adjustable from 25 MB to 500 MB. Default is 100 MB.
- Document quality: Controls the trade-off between file size and visual quality. Three options:
- High: Best looking result, least size reduction.
- Balanced: Good quality with meaningful size reduction. This is the default.
- Small: Smallest file, most noticeable quality reduction.
- Grayscale: Convert color PDFs to grayscale before uploading. Often looks fine on the reMarkable's e-ink display and makes files significantly smaller.
- Flatten: Flatten PDF layers and annotations into a single layer. Useful for complex PDFs with many layers.
- Split: Allow splitting large files into multiple parts if needed after re-encoding.
Per-upload confirmation for large files
When you drop or pick a file that is above your threshold (or a comic archive that needs conversion), the app shows a confirmation sheet before uploading. This sheet shows you the estimated output size and lets you:
- Adjust the quality preset for this specific upload.
- Turn optimization off for just this file.
- Proceed with the current settings.
Smaller files skip this confirmation and start uploading immediately.
Optimization applies everywhere on Mac
The optimizer applies across all upload methods on Mac:
- Drag and drop in the main app.
- The file picker in the main app.
- The macOS share extension.
- The Print to reMarkable print helper.
- Watched folders.
Each watched folder can also have its own optimization settings, independent from the global default. See the Watched Folders page.
Turning off optimization for a specific upload
If you want to upload a large file exactly as it is, without any re-encoding:
- When the confirmation sheet appears (for large files), set the mode to Off for this upload.
- The file uploads as-is.
Or turn it off globally in Settings > Conversion by setting the mode to Off.